drm/radeon/radeon_display: Remove unused variable 'mod'

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/radeon/radeon_display.c: In function ‘radeon_div’:
 drivers/gpu/drm/radeon/radeon_display.c:1094:11: warning: variable ‘mod’ set but not used [-Wunused-but-set-variable]

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: report to <xorg-driver-ati@lists.x.org>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_display.c

@@ -1091,11 +1091,9 @@ void radeon_compute_pll_avivo(struct radeon_pll *pll,
 /* pre-avivo */
 static inline uint32_t radeon_div(uint64_t n, uint32_t d)
 {
-	uint64_t mod;
-
 	n += d / 2;
 
-	mod = do_div(n, d);
+	do_div(n, d);
 	return n;
 }